Internal combustion engines are found in different applications and are used for many different purposes. For example, automobiles, lawnmowers, trains, pumps, and generators use some form of an internal combustion engine. The vast majority of these engines are configured to operate with a single fuel type, for example, diesel fuel. Because only a single fuel type is used in most internal combustion engines, the kinetics of the combustion reaction can be anticipated and governed by a conventional electronic control module (“ECM”).
However, in some engines (e.g., conventional dual fuel engines) a second type of fuel can be introduced to supplement or partially take the place of the first fuel in the combustion chamber. The selection of the second fuel often depends on the energy density of the fuels and/or the cost disparity between the two fuels. For example, because natural gas is generally less expensive per unit of energy than diesel fuel, some dual fuel engines have incorporated a natural gas delivery point in the air intake of the engine while still injecting liquid diesel fuel directly into the combustion chamber. The volume of natural gas delivered can range from a small percentage of the total fuel (for facilitating ignition) all the way up to a substantial percentage of the total fuel.
In many dual fuel systems, the internal combustion engine is physically retro-fitted to enable the engine to operate with two different types of fuels. However, no modifications or adjustments are made to the conventional ECM, which is responsible for governing the operation and performance of the engine. In other words, conventional dual fuel systems merely allow two fuels to be injected into the combustion chamber but fail to provide the proper governing and control structure that is desirable when dealing with the reaction kinetics of two different fuels in a single combustion chamber. Accordingly, conventional dual fuel engines often suffer from a variety of problems, including excessive engine knock, poor fuel economy (partially as a result of the ECM causing the engine to over-compensate), excessively high engine temperatures, and harmful emissions, to name a few. These problems can severely limit the amount of secondary fuel that can be substituted for the primary fuel, thus reducing the effectiveness of conventional dual fuel engines.